[3] It stars Katherine Langford, Charlie Plummer, Hayley Law, Piper Perabo, Rob Huebel and Yvonne Orji and is based on the 2016 novel of the same name by Aaron Starmer.

Dylan explains how he had begun thinking of life and how quickly it could end, and upon hearing Mara's suggestion of the incident repeating itself, realized that he needed to take action.

They begin seeing one another and attend a school football game and house party, although each is cut short when a jock, Perry Love, and drink server, Cranberry Bollinger, respectively explode, sending the attendees into a panic.

The incidents attract the attention of numerous government agencies, who place FBI Agent Carla Rosetti on the case; she enlists Mara and Tess as aid.

Realizing they should live like every day might be their last, Mara and Dylan continue seeing each other, pursuing a hedonistic lifestyle; they have sex and dance to Eighties music in an old barn.

Following Dylan's death, a despondent Mara turns to alcohol, and in the ensuing weeks drunkenly falls out with her parents and Tess, as well as accidentally breaking Agent Rosetti's car window with a stolen bottle of whiskey.

In June 2016, it was announced Awesomeness Films had acquired rights to adapt the novel of the same name by Aaron Starmer, with Brian Duffield writing the script, and ultimately directing.

[6][7] In February 2018, Piper Perabo, Rob Huebel, Yvonne Orji, Laine MacNeil, Clive Holloway, Bzhaun Rhoden, and Chris Shields were added in supporting roles.

The website's critics' consensus reads, "A dark teen comedy with an explosive twist, Spontaneous reaffirms Katherine Langford as a rising star ― and marks debuting director Brian Duffield as a filmmaker to watch.